In some types of wind turbine generators, independent pitch control can be executed in which loads imposed on the roots of a plurality of blades (for example, blade-root loads or moments) are reduced to protect equipment, and the pitch angles of the blades are independently controlled to reduce fluctuations of the loads, through a pitching operation of the blades performed in consideration of the wind speed distribution (wind shear) and the wind direction.
Limits are set on a pitch-angle command value, which is used to control the pitch angle of each blade. PTL1 describes that a limiter is provided in a wind turbine generator to limit the setting range of the pitch-angle command value, based on the magnitude relationships between an output-power set value and the rated power of the generator and between a rotational-speed set value and the rated rotor speed of the rotor.